If you think about Consumer Reports was being fair to BMW. If they based "excellent" based on Lexus as a whole, then they have just enough right to base realiability as "average" for BMW as a whole. But they didn't, they're rightfully waiting for data hoping the e90 won't follow the path of its other series stablemates.(reliability wise)

I recall that CR gave the 3er high reliability marks for the last model year they rated.
It's still not much of a trend.